Adoptive cell transfer after chemotherapy enhances survival in patients with resectable HNSCC.

OBJECTIVES: The aims of this study were to evaluate the therapeutic efficacy and to determine the immune factors for treatment success in patients with head and neck squamous cell carcinoma (HNSCC) treated with chemotherapy followed by adoptive cell transfer (ACT). METHODS: A total of 43 HNSCC patients who received radical resection and chemotherapy were analysed in this study. Twenty-one of the patients were repeatedly treated with ACT after chemotherapy (ACT group), and the other twenty-two patients without ACT treatment were included as part of the control group. To investigate the immunological differences underlying these observations, we expanded and profiled improving cytokine-induced killer cells (iCIK) from peripheral blood mononuclear cells (PBMCs) with the timed addition of RetroNectin, OKT3 mAb, IFN γ and IL-2. RESULTS: The median of progression-free survival (PFS) and overall survival (OS) in the ACT group were significantly higher as compared to the control group (56 vs. 40; 58 vs. 45 months). In iCIK culture, there was a significant reduction in CD3+CD4+ T-cell proliferation and cytokines (IL-2, TNF) production from patients who received chemotherapy compared to patients without chemotherapy. Intra-arterial infusion of iCIK, in coordination with chemotherapy, considerably rescued iCIK culture from the suppression of systemic immunity induced by chemotherapy and induced tumour regression. CONCLUSIONS: Altogether, these findings suggest that ACT is an effective neo-adjuvant therapy for rescuing systemic immune suppression and improving survival time in patients with HNSCC.

Intracellular Phospho-Flow cytometry reveals novel insights into TCR proximal signaling events. A comparison with Western blot.

Phospho-site specific antibodies become increasingly available, enabling the study of signaling events by Western blotting (WB) or intracellular flow cytometry (Phospho-Flow). Here we compared data generated by WB or Phospho-Flow regarding the kinetics and degree of phosphorylation of membrane proximal TCR signaling molecules. Phosphorylation events in Jurkat T cells were triggered by anti-CD3 stimulation (OKT3) or by oxidative stress (H(2)O(2)) and were analyzed by Phospho-Flow or WB. Both techniques showed that OKT3- or H(2)O(2)-induced, transient phosphorylation of ZAP70 or LAT was dependent on functional Lck. Phospho-Flow data revealed differences in the kinetics and the degree of H(2)O(2)- or OKT3-mediated protein phosphorylation compared with WB data. In addition, using Phospho-Flow we discovered that H(2)O(2)-induced phosphorylation of TCR signaling proteins was inhibited by small molecular weight kinase inhibitors far more potently than OKT3-triggered protein phosphorylation, despite a superior induction of phosphorylation by H(2)O(2). This finding was confirmed by WB. Interestingly, we identified by Phospho-Flow that, in P116 Jurkat cells lacking ZAP70 protein expression, H(2)O(2) potently triggered the phosphorylation of ZAP70 residues Y493 and Y292 but not Y319. The phosphorylation of these ZAP70 tyrosine residues cells was blocked by an Lck inhibitor, suggesting the existence of an Lck-coupled truncated ZAP70 protein or a novel isoform of ZAP70 in P116 cells. Phospho-Flow is a largely quantitative technology with excellent throughput, highly suited in studying the function or inhibition of TCR signaling pathways and allowing the detection of novel pathway insights. It can serve as a good complement to Western blot analysis.

Multiple sclerosis: T-cell receptor expression in distinct brain regions.

Multiple sclerosis (MS) is an inflammatory demyelinating disease where T cells attack the brain and the spinal cord. It is known that often particular T-cell clones are expanded in the target tissue, but it is still unknown, whether identical T-cell clones are present at distinct anatomical sites, or whether the T-cell spectrum is locally diverse. Therefore we compared the T-cell receptor (TCR) repertoire in distinct lesions and normal-appearing white matter (NAWM) from post-mortem brains of four MS patients. We analysed 19 lesions (inactive demyelinated, 15; slowly expanding chronic, 3; active lesions, 1) and 5 NAWM regions. The TCR beta-chain repertoire was investigated by CDR3 spectratyping. For each anatomical site 325 semi-nested PCR reactions were performed. About 800 Vbeta-NDN-Jbeta combinations were sequenced. Each of the four patients had distinct T-cell clones that were present in more than two anatomically distinct regions. These clones were not restricted to lesions, but were also present in NAWM. Some clones were present in all investigated lesions, and additionally, in NAWM sites. A single T-cell clone was detected in nine different sites in one patient. None of the clones was shared among different patients. Thus, pervasive T-cell clones exist in distinct regions of MS brain, and these clones are 'private' (unique) to individual patients. Analysis of the hypervariable NDN region revealed 'silent' nucleotide exchanges, i.e. nucleotide exchanges that code for identical amino acids. Such silent nucleotide exchanges suggest that the corresponding T-cell clones were recruited and stimulated by particular antigens. To attribute some of the pervasive clones to particular T-cell subsets, we isolated individual CD8+ T cells from cryosections by laser microdissection and characterized their TCR by single-cell PCR. These experiments revealed that at least some of the pervasive T-cell clones belonged to the CD8+ compartment, supporting the pathogenic relevance of this T-cell subset.

Sensitivity of NK1.1-negative NKT cells to transgenic BATF defines a role for activator protein-1 in the expansion and maturation of immature NKT cells in the thymus.

NKT cells are glycolipid-reactive lymphocytes that express markers and perform functions common to both T lymphocytes and NK cells. Although the genetic events controlling conventional T cell development are well defined, the transcription factors and genetic programs regulating NKT cell development are only beginning to be elucidated. Previously, we described the NKT cell-deficient phenotype of transgenic (Tg) mice constitutively expressing B cell-activating transcription factor (BATF), a basic leucine zipper protein and inhibitor of AP-1. In this study, we show that Tg BATF targets the majority of Valpha14Jalpha281 (Valpha14i(7)) NKT cells, regardless of CD4 expression and Vbeta gene usage. The residual NKT cells in the thymus of BATF-Tg mice are CD44(+), yet are slow to display the NK1.1 marker characteristic of mature cells. As a population, BATF-expressing NKT cells are TCRbeta/CD3epsilon(low), but express normal levels of CD69, suggesting a failure to expand appropriately following selection. Consistent with the sensitivity of NKT cells to BATF-induced changes in AP-1 activity, we detect a full complement of AP-1 basic leucine zipper proteins in wild-type NKT cells isolated from the thymus, spleen, and liver, and show that AP-1 DNA-binding activity and cytokine gene transcription are induced in NKT cells within a few hours of glycolipid Ag exposure. This study is the first to characterize AP-1 activity in NKT cells and implicates the integrity of this transcription factor complex in developmental events essential to the establishment of this unique T cell subset in the thymus.

Number of CD4+ and CD8+ T-cell CDR3 clonotypes expanding during acute infection of macaques with simian immunodeficiency virus.

The total number of circulating CD4+ and CD8+ T-cells undergoing clonal expansions following SIV(mac251) infection was determined using a T-cell receptor Vbeta chain (TRBV) third complementarity-determining region (CDR3) DNA heteroduplex tracking assay (HTA). This assay measures the number of newly expanding T-cell clones but not their antigenic specificity. Fewer expanding CD4+ (3-23 per animal) than CD8+ (18-37 per animal) clonotypes were observed during the acute phase of SIV infection. CD8+ T-cell expansions peaked at 4 weeks postinfection (wpi) concomitant with early reductions in viremia. Expanding clone TRBV transcripts ranged in frequency from the limit of detection of 2% to 40% of their TRBV subfamily's transcripts. The number of expanding CD4+ or CD8+ clones correlated with neither peak, subsequent slope, nor steady-state viremia. CDR3 repertoires in CD8-expressing cells in different anatomical compartments were also analyzed. Repertoires were polyclonal in the thymus, oligoclonal in mesenteric lymph nodes, peripheral blood mononuclear cells (PBMC), and spleen, and extremely oligoclonal in intra-epithelial lymphocytes (IEL) and lamina propria lymphocytes (LPL). The lack of correlation between the number of expanding T-cell clonotypes and viremia levels may reflect the highly variable selection pressure imposed on SIV by T-cell responses targeting different epitopes in outbred macaques.

Redirected T-cell cytotoxicity to epithelial cell adhesion molecule-overexpressing adenocarcinomas by a novel recombinant antibody, E3Bi, in vitro and in an animal model.

BACKGROUND: To redirect cytotoxic T cells to target a broad range of adenocarcinomas, the authors constructed a novel, recombinant, bispecific antibody, E3Bi, directed at the tumor-associated antigen, epithelial cell adhesion molecule (EpCAM), and the CD3 receptor on T cells. METHODS: T cells were prepared from healthy blood donors. The cytotoxicity of activated T cells (ATC) redirected to tumor cells by E3Bi was measured with in vitro (51)Cr release assays. In vivo studies were performed in a severe combined immunodeficient (SCID)/Beige mouse xenograft model. Tumor-bearing mice were treated with low doses (1 mg/kg) or high doses (10 mg/kg) of E3Bi along with ATC (2 x 10(9) cells/kg), and treatment efficacy was evaluated both by ex vivo tumor cell survival assay after in vivo treatments and by in vivo tumor growth delay studies. RESULTS: In vitro, targeting the EpCAM-overexpressing human tumor cell lines with E3Bi increased specific cytotoxicity of ATC by > 70% at an effector-to-target ratio of 2.5 (P < 0.001); this cytotoxicity was abolished competitively in the presence of an anti-EpCAM monoclonal antibody. In contrast, E3Bi did not enhance ATC cytotoxicity toward the low EpCAM-expressing tumor cell line. In ex vivo tumor cytotoxicity assays, a significant reduction in tumor cell survival (40% with low-dose E3Bi; 90% with high-dose E3Bi) was observed in E3Bi/ATC-treated mice compared with control mice that were treated with ATC only. In addition, SCID/Beige mice xenografted with LS174T tumors demonstrated a significant tumor growth delay (P = 0.0139) after receiving E3Bi/ATC/interleukin 2 (IL-2) compared with mice that received ATC/IL-2 alone. CONCLUSIONS: E3Bi specifically and very efficiently redirected T cells to destroy EpCAM-overexpressing tumors both in vitro and in an animal model. These results suggest a therapeutic utility for E3Bi in the treatment of adenocarcinomas.

Identical twins discordant for multiple sclerosis have a shift in their T-cell receptor repertoires.

CD4 T-cells have an important role in the autoimmune response in multiple sclerosis (MS). We investigate the possibility that a shift occurs in the T-cell receptor (TR) repertoire of identical twins discordant for MS. We compare the CDR3 spectratype distributions of 24 different TR V beta (TRBV) segments in naïve CD4 T-cells from discordant MS twins and from healthy identical twins. We also compare the CDR3 spectratype distributions in unrelated healthy pairs, formed by combining members of different healthy twins, with the CDR3 spectratype distributions in unrelated pairs of MS patients and in unrelated pairs of their apparently healthy cotwins, formed by combining members of different discordant twins. We use the correlation coefficient (r-value) as a measure of similarity of CDR3 spectratypes in each pair, and we test for the significance of the difference between r-values from the different pairs. We observe that the r-value for the CDR3 spectratype distributions among discordant twins differs significantly from the corresponding r-value for the healthy twins for two TRBV segments. Further, the r-values, for both the unrelated MS patient pairs and the unrelated pairs of their apparently healthy cotwins, differ significantly from the r-values for healthy unrelated pairs of individuals. We conclude that both the MS patients and their apparently healthy cotwins have shifts in their CDR3 repertoires. Because we study naïve CD4 T-cells, we postulate that CDR3 repertoire shifts precede MS and predispose to MS, but are unlikely to be sufficient to cause MS.

Differential expression of TcR-CD3 zeta as evidence for altered immunoregulation in preeclamptic versus normotensive women.

OBJECTIVE: The study was undertaken to exhibit and quantify the difference in modulation of CD3-zeta protein (an integral component of the T-cell receptor) in preeclamptic and normotensive women. STUDY DESIGN: Serum was collected from 10 preeclamptic and 10 normotensive women at >or=37 weeks' gestation on admission. Jurkat E-61 cells were incubated with the sera (20% volume to volume) and analyzed with Western immunoblot using mouse monoclonal CD3-zeta antibody. Enhanced chemiluminescence and densitometry were used to qualitatively measure zeta expression of the cells. A de novo flow cytometry assay was developed to quantify the difference in CD3-zeta expression of these cells. Comparisons were performed by t test (P<.05 was significant). RESULTS: Preeclamptic patient sera produced a 2.4-fold increase in CD3-zeta expression than normotensive patients on Western blot (P<.01). Flow cytometry showed that preeclamptic sera had a 1.4-fold higher expression of CD3-zeta compared with normotensive patients (P<.0003). CONCLUSION: TcR/CD3-zeta expression is normally suppressed in pregnancy. Loss of this suppression occurs in preeclamptic patients, implying increased T-cell function.

Leukocyte infiltration and inflammatory antigen expression in cadaveric and living-donor livers before transplant.

BACKGROUND: There is evidence to indicate that organs obtained from cadaveric donors may be injured as a result of inflammatory events occurring at around the time of brain death. The aim of this study was to investigate whether there are differences in the expression of proinflammatory molecules between cadaveric and living-donor livers before transplant and to determine whether there is any association with donor factors and posttransplant graft function. METHODS: A comparison of biopsies obtained before implantation from cadaveric (n=22) and living-related donor (LRD) (n=10) livers was performed. Cryostat tissue sections were stained with antibodies to leukocyte subpopulations, adhesion molecules, and human leukocyte antigen class II antigens. RESULTS: Significantly higher levels of CD3+ lymphocytes (1.5%+/-0.8% vs. 0.5%+/-0.3%; P=0.00004), CD68+ monocytes and macrophages (4.0%+/-1.2% vs. 2.7%+/-0.6%; P=0.0003), and Fas-ligand staining (4.2%+/-2.6% vs. 1.5%+/-1.1%; P=0.0003) were detected in cadaveric livers compared with LRD livers before transplantation. Furthermore, higher levels of intercellular adhesion molecule-1 expression were detected in cadaveric donor livers and found to be associated with longer periods of ventilation (P=0.01), infection in the donor (P=0.013), and administration of dopamine (P=0.03). Although there were no differences in neutrophil infiltration between cadaveric and LRD livers, significantly higher levels were found in cadaveric donors with infection (P=0.01). CONCLUSION: This study demonstrates that inflammatory changes occur in cadaveric donor livers and are associated with events occurring during the period of intensive care. These proinflammatory changes did not seem to affect the short-term clinical outcome of cadaveric liver allografts but may contribute to alloimmune responses and impairment of graft function in the long term.

A reversible functional defect of CD8+ T lymphocytes involving loss of tetramer labeling.

We have observed that human CTL clones lose their specific cytolytic activity and cytokine production under certain stimulation conditions, while retaining an antigen-dependent growth pattern. These inactive CTL simultaneously lose their labeling by an HLA-peptide tetramer, even though the amount of TCR-CD3 at their surface is not reduced. The tetramer-negative cells recover tetramer staining and cytolytic activity after stimulation with tumor cells in the presence of a supernatant of activated lymphocytes. Our results suggest the existence of a new type of functional defect of CTL. They also indicate that tetramers may fail to reveal some CTL bearing the relevant TCR, even when such functionally arrested CTL retain the potential to participate in immune responses because their defect is reversible.

IL-2 down-regulates the expression of TCR and TCR-associated surface molecules on CD8(+) T cells.

CD8(+) T cells are known to down-regulate the TCR complex upon ligation with its cognate MHC class I-peptide complex. In the present report, we demonstrate that stimulation of CD8(+) T cells with cytokines also leads to down-regulation of the TCR complex and TCR-associated surface molecules. A significant reduction of TCRalpha beta, CD3, CD8alpha and CD8beta surface expression was observed when CD8(+) T cells were cultured in IL-2 and to a lesser extent in IL-4 or IL-15. The down-regulation was apparent after 2 days of culture and was observed at IL-2 concentrations as low as 10 U/ml. Using TCR transgenic mice, we found that the down-regulation was associated with a decreased affinity of CD8(+) T cells to MHC class I-peptide complexes, as determined by MHC class I tetramer staining. Furthermore, the antigen-specific proliferation of IL-2-pre-activated CD8(+) T cells was significantly reduced compared to naive CD8(+) T cells or to CD8(+) T cells previously stimulated with peptide-pulsed dendritic cells. Moreover, only CD8alpha(high) but not CD8alpha(low) cells sorted from IL-2-activated CD8(+) T cells proliferated in response to specific antigen, although both subsets proliferated equally well to IL-2. Taken together, these data suggest that the down-regulation of TCR components and a subsequent decrease in affinity towards MHC class I-peptide complexes may be a mechanism by which TCR-dependent proliferation of non-specifically activated CD8(+) T cells is avoided.

Microemulsion cyclosporin formulation, in contrast to the old formulation, widens the T lymphocyte subsets differences between stable and acute rejection of kidney transplants.

BACKGROUND: The new cyclosporin (CsA) formulation, Neoral, has different pharmacokinetics compared with Sandimmune (SIM). Larger area under the curve (AUC) values with equivalent trough blood values are reached when Neoral is administered at equivalent doses to SIM. Previously, we showed a great diagnostic reliability when using cytofluorometric analysis from fine-needle aspiration biopsy (FNAB) samples. We investigated possible changes brought about by Neoral on lymphocyte subsets and the repercussions on the activation score cut-off for acute rejection, defined under SIM treatment. METHODS: Of 63 patients that received SIM, 40 remained rejection-free and 23 suffered one episode of rejection. Of 52 patients that received Neoral, 38 remained rejection-free. Peripheral blood lymphocytes (PBL) and lymphocytes from FNAB taken on days 7 and 14 post-transplantation and on the first day of acute rejection were analysed by flow cytometry. RESULTS: Trough blood CsA levels were not different between SIM and Neoral treatments. Among rejection-free patients, a significant down-regulation of CD3DR and of CD8DR expression on both graft-infiltrating lymphocytes (GIL) and PBL, and significant up-regulation of naïve T cells on GIL were observed with Neoral. These changes were followed by a significant down-regulation of the activation score with Neoral. Conversely, within the acute rejection group, the activation score was significantly higher with Neoral than with SIM. The activation score performed equally well in Neoral transplants compared with what we had reported with SIM. CONCLUSIONS: Our study indicates that Neoral elicits stronger immunosuppressive effects in stable patients, which eventually should translate into better clinical efficiency. However, when acute rejection supervenes, the treatment breakthrough seems stronger with Neoral. Cytofluorometric studies from FNAB samples showed that diagnostic reliability was maintained at a high level under Neoral therapy.

Human gammadelta T cells express a higher TCR/CD3 complex density than alphabeta T cells.

The aim of our study was to compare CD3 expression on gammadelta T cells and alphabeta T cells in human patients. The antigen density of TCR and CD3 on both subsets was assessed by a quantitative method in eight patients. In parallel, we developed and validated a reliable direct tricolor staining protocol that we tested on samples from hospitalized and healthy individuals (n = 60). Our results demonstrate that human gammadelta T cells constitutively express approximately twofold more of the TCR/CD3 complex than alphabeta T cells. We suggest that this enhanced expression of the TCR/CD3 complex could contribute to the higher reactivity of gammadelta T cells compared to alphabeta T cells. These clinical laboratory results confirm the fundamental data described elsewhere. gammadelta T cells deserve further clinical investigations to understand their precise role in human immunity.

Biochemical analysis of the Xenopus laevis TCR/CD3 complex supports the "stepwise evolution" model.

The TCR/CD3 complex of a cold-blooded vertebrate, the amphibian Xenopus laevis, was biochemically characterized with a cross-reactive polyclonal antiserum recognizing a conserved epitope in the cytoplasmic domain of CD3E. The specificity and utility of this reagent was validated by Western blot analysis and immunoprecipitation of the well-characterized chicken TCR/CD3 complex. Cross-reactivity with the X. laevis CD3E protein was demonstrated by specific staining of sorted CD8+ cells. Immunohistology on both tadpoles and adult tissues suggests this antiserum will be instrumental in the localization of Xenopus T cells and most likely NK cells. Double staining of tissue sections with an anti-CD8 monoclonal antibody confirmed that this staining is specific. The antiserum was also used for the biochemical analyses of X. laevis TCR/CD3 complex. The 75-kDa alphabeta TCR heterodimer could be separated into a 40-kDa acidic TCR alpha chain and a 35-kDa basic TCR beta chain. Two CD3 proteins, both comigrating at approximately 19 kDa, were associated with the TCR heterodimer. Removal of N-linked carbohydrates yielded CD3 proteins of 19 kDa and 16.5 kDa, most likely representing the CD3epsilon and CD3gamma/delta homologues, respectively. An additional band of 110 kDa represents a multimeric complex of the TCR heterodimer covalently linked to a CD3 dimer. These properties of the Xenopus TCR/CD3 complex substantiate a stepwise evolutionary model for the CD3 protein family.

Down-regulation of macaque gammadelta + T cells in lymphoid compartments after rectal infection with SIVsmmPBj14.

The dynamics of T cells expressing the gammadelta T-cell receptor in mucosae and other compartments during the course of human immunodeficiency virus (HIV)-1 infection are poorly understood. To examine the impact of an acquired immunodeficiency syndrome virus on the gammadelta + T-cell population, rectal inoculation of macaques with simian immunodeficiency virus (SIV)-PBj14 was used as a model. After rectal inoculation, five macaques were sacrificed on days 4, 5, or 7 and then assessed for changes in the gammadelta T-cell receptor repertoire in different lymphoid compartments. There was decreased representation of gammadelta + T cells in the intestinal mucosae, blood, and spleens. Overall, the reduced number of total gammadelta + T cells was consistent with decreases in the Vgamma or Vdelta T-cell sub-populations. Nevertheless, there was no consistent deletion or expansion of a selected Vdelta + or Vdelta + cell sub-population. These results demonstrate that SIV-PBj14 replication and dissemination after mucosal inoculation resulted in a decline of detectable gammadelta + T cells, suggesting that macaque gammadelta + T cells are susceptible to down-regulation or destruction during acute SIV-PBj14 infection.

Specific cytolytic T-cell responses to human CEA from patients immunized with recombinant avipox-CEA vaccine.

Avipox viruses are replication-defective members of the poxvirus family. Avipox-derived vectors such as ALVAC (canarypox) and fowlpox have the ability to infect mammalian cells, including human cells, but do not replicate. The first clinical trial of an avipox recombinant vaccine for patients with advanced carcinomas has recently been conducted using the ALVAC vector and the human carcinoembryonic antigen (CEA) transgene (designated ALVAC-CEA; J. L. Marshall et al, J. Clin. Oncol., 17: 332-337, 1999). The T-cell responses elicited by patients before and after vaccination with the ALVAC-CEA recombinants are characterized in this report. Pre- and postvaccination peripheral blood mononuclear cells (PMBCs) of the eight patients positive for HLA-class I A2 allele, were incubated with the HLA-A2-CEA peptide CAP-1 and interleukin 2. In no cases using prevaccination PMBCs could cultures be established that had the ability to lyse C1R-A2 target cells pulsed with the CAP-1 peptide. However, T-cell cultures from seven of eight of these same patients, obtained from PBMCs after ALVAC-CEA vaccination, were shown to lyse C1R-A2 cells only when pulsed with CAP-1. Moreover, all seven of these T-cell cultures were shown to lyse allogeneic human carcinoma cell lines (SW1463 and SW480) that were both A2+ and expressed CEA; an allogeneic tumor cell line (LS174T) expressing CEA that was negative for A2 expression was not lysed. HLA-A2+ and CEA+ autologous tumor cells were also capable of being lysed by CEA-specific T cells from this patient. Analysis of this CTL line also revealed the expression of several homing and adhesion-associated molecules. Fluorescence-activated cell sorter analysis of the T-cell lines established from patients after ALVAC-CEA vaccination revealed that most were CD8+/CD4-, but many also had a CD8+/CD4+ component. Analyses of T-cell receptor Vbeta usage of several of the CEA-specific CTL lines showed a relatively diverse Vbeta pattern. These studies demonstrate for the first time the ability to vaccinate cancer patients with an avipox recombinant and derive T cells that are capable of lysing allogeneic and autologous tumor cells in a MHC-restricted manner. These studies thus form the rationale to use such replication-deficient recombinant vaccines in future cancer vaccine trials.

Extracellular signal-regulated kinase (ERK) activation by the pre-T cell receptor in developing thymocytes in vivo.

The first checkpoint in T cell development occurs between the CD4(-)CD8(-) and CD4(+)CD8(+) stages and is associated with formation of the pre-T cell receptor (TCR). The signaling mechanisms that drive this progression remain largely unknown. Here, we show that extracellular signal-regulated kinases (ERKs)-1/2 are activated upon engagement of the pre-TCR. Using a novel experimental system, we demonstrate that expression of the pre-TCR by developing thymocytes induces ERK-1/2 activation within the thymus. In addition, the activation of this pre-TCR signaling cascade is mediated through Lck. These findings directly link pre-TCR complex formation with specific downstream signaling components in vivo.

Type II collagen is a target antigen of clonally expanded T cells in the synovium of patients with rheumatoid arthritis.

OBJECTIVE: To investigate whether type II collagen (CII) is recognised by oligoclonally expanded synovial T cells of patients with rheumatoid arthritis (RA). METHODS: Peripheral blood mononuclear cells (PBMC) from 15 RA patients were stimulated with CII in vitro. T cell clones expanded by such stimulation were compared with the clonally expanded synovial T cells by using T cell receptor (TCR) B chain gene specific reverse transcription-polymerase chain reaction and subsequent single strand conformation polymorphism analyses. RESULTS: Stimulation of the heterogeneous peripheral T cells with CII induced clonal expansion of T cells. In three of 15 patients, a proportion of these clones (approximately 17% to 25%) was found to be identical to expanded T cell clones in the synovium in vivo. CONCLUSION: T cell clones that had TCR CDR3 sequences identical to those induced by purified CII were found in a proportion of RA patients. This finding suggests that CII is recognised by T cells that accumulate clonally in RA joints. Oligoclonal T cell expansion in RA joints is probably driven, at least in part, by intra-articular components such as CII.

Human immunodeficiency virus type 2 produces a defect in CD3-gamma gene transcripts similar to that observed for human immunodeficiency virus type 1.

T cells are central players in the immune response to infectious disease, with the specificity of their responses controlled by the T-cell receptor (TCR)/CD3 complex on the cell surface. Impairment of TCR/CD3-directed CD4(+) T-cell immune responses is frequently observed in individuals infected with human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2). Virus replication is also regulated by T-cell activation factors, with HIV-1 and HIV-2 responding to different TCR/CD3-directed cellular pathways. We previously demonstrated that HIV-1 infection of the human interleukin-2-dependent CD4(+) T-cell line WE17/10 abrogates TCR/CD3 function and surface expression by a specific loss of CD3-gamma gene transcripts. In this study, we show that HIV-2 provokes the same molecular defect in CD3-gamma gene transcripts, resulting in a similar but delayed progressive loss of TCR/CD3 surface expression after infection.